UNIT – IV Input Devices: Keyboard, Mouse, joystick, MICR, OCR, Barcoding, Speech Output Devices: Printers, Plotter, VDU, Graphic Display Devices. INPUT DEVICES The computer will be of no use unless it is able to communicate with the outsideworld. Input/Output devices are required for users to communicate with the computer. In simple terms, input devices bring information INTO the computer and outputd evices bring information OUT of a computer system. These input/output devices are also known as peripherals since they surround the CPU and memory of a computer system. Input devices are hardware devices that allow data to be entered into a computer. The computer will be of no use if it is not communicating with the external world. Thus, a computer must have a system to receive information from the outside world and must be able to communicate results to the external world. Thus, a computer consists of input/output devices. Input and output devices can also be written as I/O devices. Input and output devices of a computer system are the devices that connect you to computer. Input devices let you to transfer data and user command into the computer system. I/O devices are used to interact with the computer system. For example, you can type in data by using a keyboard, or you can input data in picture form by using a scanner in computer system. An input device presents data to the processing unit in a machine-readable form.Although the keyboard is a common input device for a small computer, a systemmay also support various other input devices such as Optical CharacterRecognition (OCR), Magnetic Ink Character Recognition (MICR), mark sense reader, etc. Manual Input devices: Data is input into the computer by hand. Manual input devices require humans to do most of the work needed to get data into the system. (eg.) Keyboard, Mouse, Tracker ball, Joystick, graphics tablet, digital camera, Webcam, microphone, touch screen, chip and pin Direct Input devices (automatic input devices): Data is input into the computer directly by a machine or device. Direct input devices do not require much human interaction to get their data into a computer system. (eg.) Barcode scanner, Magnetic stripe reader, OMR reader, OCR reader, biometric scanner, Sensor. 1 | III UNIT: NME -1: INFORMATION TECHNOLOGY KEY BOARD The keyboard is the most common and widely used input device. It is made up of buttons called 'keys'. The keys are arranged into sections: • Alphabet keys • Function or F keys (F1, F2, F3) • Numeric keys (one set above the alphabet keys and a numeric keypad on the right) • Arrow keys • Command keys (insert, delete, home, end, page up/down) Keyboards are used to input Text, numbers and instructions into the computer. Most keyboards use a QWERTY key layout. This name comes from the first six letters on the top row of the alphabet keys. Special keyboards called “Ergonomic keyboards” have built-in-hand-rest which prevents health issues such as RSI (Repetitive Strain Injury).Ergonomic keyboards have natural shape to reduce stress on wrist and hands. A concept keyboard is a specialized keyboard with no pre-set keys. It relies on a touch sensitive screen with the key or overlay displayed on the screen. Each key can be programmed with a wide range of different functions. The overlay is often used as a quick and easy way to input items with without needing to type anything or use a mouse. If you go to a fast food restaurant, the assistant will normally be using a concept keyboard. Pictures and icons can replace words and means that the assistant can quickly enter the order without having to use a keyboard. Numeric keypads are used for entering numbers into a computer system. Some numeric keypads allow you to enter simple text and symbols. Numeric keypads are found in ATM (Automatic Teller Machines), telephones and chip and pin device. Electronic point of sale (EPOS) terminals has numeric keypads in case the barcode reader fails. Uses of keyboard: • Keyboards are used to enter text, numbers and instructions into applications like Word and Excel. • Keyboards can also be used to enter commands(keyboard shortcuts) into the computer Advantages of keyboards: 1. Enable fast entry of data. 2. Most computers come with a keyboard supplied 3. People need very little training to use keyboard. 2 | III UNIT: NME -1: INFORMATION TECHNOLOGY Disadvantages of keyboards: 1. Keyboards are large and can take up a lot of desk space. 2. Keyboards are not suitable for creating diagrams. 3. Excessive use can lead to health problems such as repetitive strain injury (R.S.I.) 4. Entering data is slow compared to automatic methods. For example a barcode scanner will input data into the computer almost instantly. Alphanumeric Keypad It consists of keys for English alphabets, 0 to 9 numbers, and special characters like + − / * ( ) etc. Function Keys There are twelve function keys labeled F1, F2, F3… F12. The functions assigned to these keys differ from one software package to another. These keys are also user programmable keys. Special-function Keys These keys have special functions assigned to them and can be used only for those specific purposes. Functions of some of the important keys are defined below. Enter It is similar to the ‘return’ key of the typewriter and is used to execute a command or program. Spacebar It is used to enter a space at the current cursor location. Backspace This key is used to move the cursor one position to the left and also delete the character in that position. Delete It is used to delete the character at the cursor position. Insert Insert key is used to toggle between insert and overwrite mode during data entry. Shift This key is used to type capital letters when pressed along with an alphabet key. Also used to type the special characters located on the upper-side of a key that has two Characters defined on the same key. 3 | III UNIT: NME -1: INFORMATION TECHNOLOGY Caps Lock Cap Lock is used to toggle between the capital lock features. When ‘on’, it locks the alphanumeric keypad for capital letters input only. Tab Tab is used to move the cursor to the next tab position defined in the document. Also, it is used to insert indentation into a document. Ctrl Control key is used in conjunction with other keys to provide additional functionality on the keyboard. Alt Also like the control key, Alt key is always used in combination with other keys toperform specific tasks. Esc This key is usually used to negate a command. Also used to cancel or abort executing programs. Numeric Keypad Numeric keypad is located on the right side of the keyboard and consists of keys having numbers (0 to 9) and mathematical operators (+ − * /) defined on them. This keypad is provided to support quick entry for numeric data. Cursor Movement Keys These are arrow keys and are used to move the cursor in the direction indicated by the arrow (up, down, left, right). MOUSE Mouse is a device that controls the movement of the cursor or pointer on a displayscreen. It is a small object you can roll along a hard and flat surface. As youmove the mouse, the pointer on the display screen moves in the same direction.Mouse contains at least one button and sometimes as many as three, which havedifferent functions depending on what program is running. The mouse is a small device used to point to a particular place on the screen andselect in order to perform one or more actions. It can be used to select menu commands, size windows, start programs etc. 4 | III UNIT: NME -1: INFORMATION TECHNOLOGY The most conventional kind of mouse has two buttons on top: the left one being used most frequently. Mouse Actions Left Click :Used to select an item. Double Click : Used to start a program or open a file. Right Click : Usually used to display a set of commands. Drag and Drop : It allows you to select and move an item from one location to another. To achieve this place the cursor over an item on the screen, click the left mouse button and while holding the button down move the cursor to where you want to place the item, and then release it. Types of Mouse: Mouse could be mechanical, optical or cordless types. Further information regarding these types are as follows: Mechanical Mouse : Mechanical Mouse uses ball for the movement of cursor on the computer screen. When the ball is rolled in any direction, a sensor of the mouse detects it and also moves the mouse pointer in the same direction. Optical Mouse : Optical Mouse uses Laser rays for the movement of cursor on the computer screen. It is an advanced pointing device. Movement is detected by sensing changes in the reflected light rather than the motion of a rolling sphere. Cord-Less Mouse : Cord-Less Mouse is battery driven and does not need any wire for the physical connection with the motherboard. It transmits data through infrared or radio signal. Computer mice are very useful in designing pictures and graphs and computer and video games by multimedia designers. A Mouse pad is required to move the mouse because it provides a smooth surface. However, an optical or laser mouse doesn’t require a mouse pad. Uses of Mouse: 1. Opening, closing, Maximizing and Minimizing programs and files. 2. Moving, grouping and deleting files 3. Controlling a pointer on a screen to select icons or move around the page. 4. Editing images in terms of size and position on the screen.